NYClark, the Welsh have taken to kilts during the past century (one of our Welsh members might give you a more accurate period for this).
First the Irish took to wearing black kilts at the end of the 19th century, then the Welsh at some later stage, and then also the Cornish.
Tartans for these ethnic groups came later.
There are now numerous Welsh tartans to choose from – I could send you a list if you are interested.
Regards,
Mike

PS: My favourite colour is royal blue, and the Tardis is not a bad example. The tartan I designed for my family has red, yellow, white and blue, as well as a selection of background colours (light blue, white, brown and darkish red). So I think I would escape looking like a postbox or a Tardis, even though I have these colours in the setts.